def read_store_promotions(product_name):
    """
    根据商品名称读取商品促销信息.
    """
    file_path = 'store_promotions.txt'
    try:
        with open(file_path,'r',encoding='utf-8')as file:
                  promotions_content = file.readlines()
                  filtered_content = [line for line in promotions_content if product_name in line]
                  if filtered_content:
                        return ''.join(filtered_content)
                  else:
                        return f'未找到与"{product_name}"相关的促销信息。'
    except FileNotFoundError:
        return '促销信息文件未找到,请检查文件路径是否正确。'
    except Exception as e:
        return f'读取促销信息时出错: {str(e)}'